The grotto was set up outside the Business Department. Credit: PA
Striking Post Office workers set up a Santa's Grotto, complete with live reindeer, outside a government department at the start of a week of industrial action over jobs, pensions and branch closures.
The Communication Workers Union staged the festive protest outside the central London headquarters of the Business Department, including fake snow.
The union handed in more than 70,000 post cards signed by members of the public across the country in support of their campaign.
General secretary Dave Ward warned that the future of the Post Office in high streets was at stake because of the franchising of Crown Post Offices to retail firms such as WH Smith.
The union claimed a fresh wave of closures is set to be announced in the new year.
The Post Office said around 50 branches were closed by the strike.